Apparatus for pyrolytic conversion of hydrocarbons



K. M. WATSON 2,506,123

APPARATUS FOR PYROLY-TIC CONVERSION OF HYDROCARBONS May 2, 1950 Filed June 27, 1947 a 1 a E S G 2 T m 6 w M. m mm E A 0 W U m UZ U L 7.. I, N 0 N F .X. E L m G S E R R E 3 V 3 No 1 mm a T w w m D B 3 E a E E E 2 AG m um m P T 6 A E L... 5 E E A 2 T c t m 2 w U T W W... A 7 S F S S W Y 3 5 r rr7/// rfifiwivrv r nvufl 7/ M )1 a mi /AM- o E S m 9 h m N N a R m5 4 4 I E ST 6 2 V RC 2 N 2 v U E Nm R M R O VD U E A E L W: v A M ii? CDUIIL W A y W CHARGE OIL INVENTOR- AIR ATTORNEYS Sm I chamber..

difiiculties have been experienced; 1 p eration of the catalyst. ,The presen inyentien p vi an i re ls ara e theat e-the ii tisu e are voi ed- The apparatus of my present inyention. is:. 1 especially -adapted;. o the- 0am 1n .fpr e v'd s ribe en eeim application .Serial No 75" elevated temperature I acqntinuqus, verticalse nset hed 9 11 11 .downwars yhr us a ve ically h her having- ,at. least.one relatively marrow hori- ZOllltflL dimension. ,The.cpmzersiomreaction; and

catalyst, are; successively -efififited in elongated. body of,-.-catalyst..a13hee passed irom "the; bottom..-0fithE;;.QQ1umn I regenerating chamheniydiereinrnesidual canle mls burned from the catalyst, and .also..-,an;tcata1.5

Patented May 2, 1950 APPAnn'rns FOR rimom'rro CONVERSION om -rnnooaimoms .Kenn thtM skaw ts essignor :This' invention re1ates.;.tothe nrr l-yt 001. .Nersi'on. of hydrocarbons and proyides tan .provedapparatus especiallyedapted. tq the coartying. outof. such pyrolytic conversioniprocesses imzohzing. the use-10f. a solid catalyst.

Insuch operations, a. carbonaceous. deposit .is formed on-.-the solidcatalyst during the hydrocarbon .conversion and :the catalyst v-mustbe periodically =regenerated to restoreaits catalytic efiectiveness.

In onemethod of opemtionv previously prov posed, the'hydrocarbon to-..be converted ispassed continuously upwardly through a downwardly -grav itating bed-oi"- catalyst; in granularonpelleted worm, 113 a vertically elongated conversion cham- 5-1.

her or largetransversedimension, the catalyst 7 being continuouslywithdrawrifrom the'lowerend cfthe chamber, regenerated, and returned to the upper end of-the chamber. The regeneratiox-i is by 'passing the hot, catalystdowhwardly thfgugh asim-i-la-r vertically elongated chamber counterc r e s eam-9 rguchoperationshave entailed egxpensiye and tr ublesom mechan c ce retor n ans wfiw .ve ine h c t yst. i pinwthc w en i'o th eonversion chamber to the topofthe regenerating chamber and again from the lower end ffthe regenerating chamber to. the top ofi the. converteam -$231 .88

fines fi ormed by attrition are Separated from, the

lyst by blowingllwith additionalair;

rot .regeiierated catalyst is passed frqm generating. chamber into. a stream of. ma 6- Y ori -vapors to; be proc'essed and is. caughtpp by'the. apors and carried insuspens'ionupwardly 1 an enlarged chamben. positioned at an} l'- tee. s e -m ntl erre n hs n ate bet a in which-t c t y fq .Qklik :spen-sipn.andfiowsthereirom hygravity;onto

cup-per of the-vertically elongatedeatalfist ViAccording to amethodoj operation specifically described in said application, the hydrocarbon .y-apors separated from the catalyst pass from. the

.en-largedych amber andarerepeatedly passed back effected by burning cffthe-carbonaceous deposit- .andjorth through the upper portion: of thehot catalyst-bed, at progressively diff ere nt elevations; ,wherehy conyersionof the hydrocarbons is citected with the resultant v deposition of carjbonao'eous material: on the catalyst. Air, or other .nxi-dizing gas,.,is similarly passed back andiqrth through. the; lower portionof the hot catalyst-tied 125 at progressively different elevations, .with a;..e-

sultant burning off from the catalyst .0fza.,.-st1b- :stantia'llportion of the carbonaceous: deposit.

I -hehot. partially regenerated oatalyst,. aspreviousl y' noted, is-withdrawn. from the lower..por-

periencedin effecti g unitormcontact. between the ;hydroearbqn vaporsigand the catalyst Joy reason of the .tende c y of! he yapor'sto channel upwardly through this -bed bii cat he ew th c o nset alsoma substantial, amount ofirege nera tion of- .--t

D culties havei alsohbeen .eX-

aused; .to gravitate as;

tion of the verti-cally elongated chamber,..suspended in a gaseous carryingmedium, .adiviantag'eously air, and carried in suspension-to the separate regeneratihg chamber, wherein resi'dual carbori' is burned from the catalyst by contact h airand frops which the regenerated catalyst "j 'retiirhed to' theye'rti'cally elongated'ca st bedfg asj ust noted. Heatfor efl ecting the'conversi on is supplied; large measure; by the burning 6 the carbem bu der s d .1it. n ';l i? r y be sum e Wh u e b preheati l'ei r sa onth r o v ep r r fin roman by ac toneu in tr c g of thecatalyst are carried off from the jeyclelinsuspensionin flue gases passing fronrjtlie zonfe: oi finallregeneration.

The. hydrocarbon vapors to beconverted n ay e passed. throughrthe catalyst,bed at progresat minimize intermixing of regeneration gases and hydrocarbon vapors.

The effecting of the regeneration of the catalyst in stages, as just described, provides a particularly advantageous method of removing catalyst fines from the cycle, and a very complete and uniform regeneration of the catalyst is effected. Further, means are provided whereby excess air may be passed in contact with the catalyst in the final regeneration, to insure complete removal of carbonaceous deposit, without danger of excess oxygen becoming admixed with the hydrocarbon vapors.

In a particularly advantageous method of operation in accordance with my invention, the hydrocarbon vapors are repeatedly passed through the column of catalyst, at progressively lower levels in the upper portion of the catalyst bed, and the regeneration air is passed through the catalyst, at progressively higher levels in the lower portion of the catalyst bed. By this procedure, a zone of low pressure is created at the intermediate portion of the bed, both'with respect to the hydrocarbon vapors, and the gaseous products of the combustion, and the tendency of the gases and vapors to become intermixed is minimized.

It is also particularly advantageous to inject an inert sealing, or stripping, gas into the zone intermediate the conversion and regenerating sections. This serves, further, to prevent mixing of combustion gases and hydrocarbon vapors and also serves as a stripping medium for stripping from the spent catalyst readily vaporizable hydrocarbons.

' *A large amount of heat is liberated in the burning of the carbonaceous deposit and care should be exercised to avoid over-heating of the catalyst. It is usually advantageous to extract heat from the beds of catalyst undergoing regeneration in 'an' amount suiiicient to avoid excess temperaof the catalyst bed and coordinating therewith the rate of flow and number of passesof the hydrocarbon vapors and regenerating air there- ,through, the catalyst will be substantially spent and ready for regeneration by the time it reaches the lower end of the reaction zone and a major portion of the carbonaceous deposit formed thereon will be burned on upon reaching the lower end of the regenerating zone of the catalyst column.

The optimum rate of downward flow of the catalyst bed will depend primarily upon the type of catalyst employed, the type of hydrocarbon being converted, operating temperatures, the rate 'of hydrocarbon feed, the extent of the required reaction, the, depth of cracking, for instance, the number of passes through the catalyst and the thickness of the catalyst bed. The optimum rate of catalyst flow for any particular operation is readily determinable by simple tests and is, with advantage, controlled by regulation of flow of catalyst from the lower end of the regenerating zone by means of a suitable valve arrangement.

' By-efi'ecting the final regeneration of the catalyst in a separate chamber, as just described, the regeneration of the catalyst may be controlled indepeiidently of the rate of downward flow of the vertically elongated catalyst bed.

The apparatus is applicable to various types of hydrocarbon conversion and is adapted to the use of various solid catalysts in granular or pelleted form. The invention will be more particularly described and illustrated with reference to the accompanying drawing of which:

Figure 1 is a somewhat fragmentary vertical, sectional View, and

Figure 2 is a transverse section along the line 2-2 of Figure 1.

The part indicated by the reference numeral l is a cylindrical casing, advantageously of sheet metal, enclosed at its upper end. Coaxially positioned in casing l are cylindrical casings 2, 3, and 4 of progressively smaller diameters which, together with the outer casing, form annular chambers 5, 6 and 1 and an interior cylindrical portion 8. The intermediate annulus 6 is substantially unobstructed for its entire height. The outerannulus 5 is completely obstructed by a plurality of vertically spaced partitions 9 of considerable depth, forming a plurality, of vertically spaced chambers II]. The inner annulus l is similarly divided into a plurality of vertically spaced chambers H by similar partitions or spacers l2.

Each of the chambers l0 and H is connected with the annulus 6 through louvers, the slats of which project upwardly and outwardly from the annulus 6 into the respective chambers.

The casings 2, 3 and 4 terminate short of the upper end of the cylinder formed by casing I so as to form a large cylindrical chamber l3 in the upper portion of the apparatus. The uppermost of chamber I0 is in open communication at its upper end with chamber i3. The annulus 6 is likewise, in open communication at its upper end with chamber l3. The upper end of the uppermost chamber H and the upper end of the inner cylinder 8 are closed off from chamber l3 by partition l4. An elevator conduit l5 extends upwardly through the inner .chamber 8 and leads into chamber [3 through an opening in partition I4. The lower end of elevator conduit I5 is connected with a source of vaporized charge oil, not shown, and also through conduit [6 with the lower portion of a regenerator I1, which regenerator may be of conventional type.

The lower end of annulus 6 opens into a conical hopper member N3, the lower ends of which are connected by conduit 19 with conduit 20 which is, in turn, connected with the lower end of conical member 2| forming the lower portion of the regenerator H.

The conduits l9 may be provided with valves 22, which may be of conventional type, advantageously a conventional slide valve, for regulating and controlling the flow of catalyst through conduits I9.

The spacers, or partitions 9 and I2 are, with advantage positioned somewhat as shown in the drawing so as to formchambers Hi and H in staggered positions such that the lower end of a given chamber I0 is directly opposite the upper end of the next lower chamber H and the lower end of said chamber II is directly opposite the upper end of the next lower chamber ill. The spacers 9 and I2 are, for clarity, shown in the drawing as solid sections, but it is to be understood that they may be either solid or hollow.

Further, for reduction in weight and in material used in fabrication, the respective casings l and 4 may be discontinuous at the points of the respective spacers.

swoon-as in operation, thexannulus-"i is rfllled :with granular catalyst, for instance, by charging the catalyst through an opening, not shown, in the top. of the apparatus, adapted to 'be sealed in operation. vaporized hydrocarbon oil to be processed is charged through line l5in which it picks up in suspension, catalyst passing downwardly from the 'regenerator 4'! through conduit l6 'a't*'a' rate controlled 'by "adjustable valves 23. The hydrocarbon vapors carrying the catalyst in suspension pass upwardly through theelevator conduitinto chamber 13 wherein the catalyst drops out of suspension by reason of-decreased "velocity of'the vapors and fallsonto-abed' of catalyst maintained in chamber -13 irom which the catalyst jflows into the annulus *6,-'-keeping it continuously 'filled with the --cat alyst.

"Separated hydrocarbon vapors I pass from chamber 1 3 into the upper end of ='the*-upper-most chamber l 0, and, from thence, the -vapors pass, by-"way-o'f the louvers, through the bed of catalyst inannulus fiand into the upper-end of the uppermost chamber l I. From the lowerpor- =ti'on of said chamber -=l-"l,*'the vapors pass back through *the body of catalyst into the next lower chamber HI, and so 'back and-forththrough the *body--of catalyst, at progressively lower levels, until the vapors reach an intermediate chamber ll! from which they are withdrawn through one 'o'f the "valved imes 24' to-a 'fractionating apparatus, not shown. In the drawing, a plurality p'fconversion product draw-ofl lines 24 areshown leading "from progressively "lower chambers I. This is 'advantageous as; it permits withdrawal of conversion products at selective levels from :the reaction "zone thereby varying "the space velocities of r the operation :and also varying the depth of :the intermediates sealing and :stripping zone, subsequently described.

The catalyst which has-" been substantially spent continues downwardly throughannulus 6 and is stripped of "readily vaporizable hydro- --carbons "remaining thereon by :a "stripping gas .or vapor, steam, "for instance, introduced into a'still lower chamber I D through-lines 25.

Air is passedlinto thetlowermost*chamber l0 :throug'h lines 26 flows therefrom :by way of the .jlouvers, through the "bed of catalyst into 'the lowermost chamber II and *back through the "catalyst into the next higher chamber -'l0, and so back' and forth through the catalyst,- at progressively higher levels, until "it ;reaches aan intermediate chamber l 0, -below "that intowhich the'stripping medium is injecte'd, 'an'dtthe 'fiue gases- -pass therefrom through'conduits 21 to a 'e's'tack, not shown in' -thedrawing.

' The air passingincontact with the 'hot'catalyst results in-theburn'ing of the major-portion of the carbonaceous depositiormed :on the-catalyst during the hydrocarbon conversion. Excess heat "The' partially regenerated 'catalystpasses -from' "thelower end of "theregenerating 'vzone through perforations in a series of "distributing plates 29 "so positioned as to"permit;thefifiovwof"catalyst therethrough ataretarded rata dependent upon the "angle "of" repose-"of" the catalyst, and also' to retard the passage-0f air upwardly ftherethrougln from conduit 20, asunderstood by the art. Fromi thence, the catalyst flows through the annular connection '30 into 'hopper l8 and through the conduits l-9 into the stream of air passing? through-conduit 20 and is carried therebyin-sus' pension upwardly into the regenerator I1.

The regenerator I! may be of conventional type and may beprovided with means for cooling? the body of catalyst undergoing regeneration by continuously withdrawing a portion thereof through conduit 3|, cooler 32, advantageously a waste heat boiler and conduit 33 into the "stream of air passing to the regenerator I! through conduit 20, and is returned tothe regenerator IT in suspension in; the air, together with partially regenerated catalyst-fromthe annulus 6.

Residual carbon isburned fromthe catalyst-in theregenerator I1 and the products of combustion pass from the upper end through cyclone type separator as, for the separation of coarser particles of suspended catalyst, which are re turned to the dense phase "body of catalystin the chamber, ,and the products of combustion passed therefrom carrying catalystfines in suspension through conduit ,35 to a precipitator or staok not shownin the drawing. ,Fresh catalyst maytbe supplied as required during operation through :conduit ,36 at Ya rate controlled 31); valve 36a.

.Therate of now of the catalyst from the lower end ,of ,catalyst bed in annulus 6 may alsogbe controlled and regulated, in conjunction with platesi2 9 and valve .22, orin lieurthereoi, by means of..a valve, arrangement positioned just belowlthe annular connection ,38. This valve mechanism comprises an annular .flat ring .member .31 o! somewhat greater width than the annulusfill, ,positioned directly below and spaced from .the .lower end thereof. The ring ,3! -;is adjustably supportedby a plurality of shafts 38 extending .downwardly through the wall of hopper l8 and sealed bysuitahleglands 39. The length pie-the shafts 38 may be adjusted by means of turn :bucltles Ail and the lower ends of the, shafts are .connectedbylinkages-M to eccentrics. llfhe -eccentrics 42 are =-connected by suitable means, HQtv-ShOW-Il, ,so-that they willoperate togethemto rimpart -an-.o,scillatory" motion to ring 31, adjust --;ments,=in;;level of rings? and of its distancewfrom sthe lower end of annulus being made by; the v-turn'bucklesflll.

.Inthevalve arrangement shown, the :ring- =31 will completely shutoff the flow of catalystewithout requiring mechanical'sealing ;of the valve.

,By raising :the ring to a :point' where its edges sintercepttheangleof reposeof the catalyst flow.- :;ing ffromsannulus 3%, flow is completely stopped. This method :of flow controlis particularlyadvantageous .-as it avoids acrushing the catalyst. The rate of catalystrfiow is determinedi'by-tthe height of the ring and the oscillatory :motion 'maintains uniform flow at v.all points ,,around the annulus 3E3.

' The thickness of theannulus 6.- may aloe varied over a considerablerange, the'optimum'rzthicle- -ness dependingupon other operatingrconditions. Generally, its -thic-kness :is,-.withsadvantageeabout -l to zfeet. The depth-of thespacers Ill-and "12 is, with advantage, somewhat greater than the "immediately above or below --'it rather -r-than V chamber l3.

through the catalyst bed to the opposite chamher.

4 The vertical spacing between the outer and inner annular chambers, respectively, is shown in the drawing as somewhat greater than the thickness of annulus E. It will be understood that the spacings are, with advantage, of greater relative vertical dimension than shown in the drawing, advantageously being considerably greater than the thickness of the catalyst bed, as previously noted.

With the exception of the intermediate zone, some by-passing of the gases or vapors from one zone to the next higher or lower zone does not seriously interfere with the operation. However, mixing of combustion gases from the regenerating zone with the hydrocarbon vapors should usually be avoided and, for this reason, it is particularly advantageous that the spacing just above the regenerating zone be considerably greater than the path horizontally through the catalyst bed.

The apparatus specifically shown in the drawing provides for four to six passes of the hydrocarbon vapors and for four passes of the regenerating air through the catalyst bed. Frequently, a greater number of passes is desirable and is within the contemplation of my invention. Figure l of the drawings is somewhat fragmentary indicating intervening sections of the apparatus of similar design.

Provision for the injection of sealing or stripping gas between the conversion and regenerating zones may frequently be omitted, particularly where the amount of air passed through the regenerating zone is so controlled that upon reach- .ing the upper end of the regenerating zone, the

"such diameter relative to the volume of hydrocarbon vapors to be charged therethrough as to effect a high velocity of flow so as to entrain the catalyst particles and carry them upwardly into Generally, the superficial velocity of the rising vapors should be within the range of 10 to 50 feet per second, the optimum velocity depending, in large measure, upon the size and density of the catalyst particles and the relative proportion of catalyst to be carried thereby.

The apparatus of the invention is adapted to the use of various types of catalyst, for instance, natural or synthetic earths, silica gel, and the like, or various inert carriers having active catalysts deposited thereon. The size of the particles of catalyst is, with advantage, of a mesh within the range of 25 to 40, though catalysts of larger or smaller particle size may be employed. Pelleted catalyst as coarse as 4 to 10 mesh may be employed with advantage. Usually,

powdered catalyst, such as used in the fluid catalyst processes, is less desirable because of a tendency of the catalyst particles to be carried out of the catalyst bed along with the gases and vapors, but may be used in conjunction with relative low gas and vapor velocities through the catalyst bed.

Operating conditions are generally subject to considerable variation depending upon the particular catalyst employed, and the nature and the extent of the desired reaction. In cracking gas oil, for instance, using a silica-alumina type catalyst, the temperature of the reaction zone is, with advantage, maintained within the range of about 750 to 950 F. and the pressure within the range of about 10 to 15 pounds per square inch. In the regenerating zones, a temperature within the range of 900 to 1150 F. is usually satisfactory.

The temperature in the reaction zone is controlled in large measure at least by the temperature of the catalyst and the proportion thereof introduced into the charge oil and also the extent of preheat of the, charge oil. The temperature of the catalyst undergoing regeneration is controlled by the extraction of heat therefrom, as previously described, any desired number of cooling coils being used for that purpose in the regenerating zone of annulus 6 and any number of coolers or waste heat boilers being used in connection with the final regeneration in regenerator 11.

By use of the present apparatus the extent of contact between the catalyst and the hydrocarbon vapors being converted and also the catalytic activity of the catalyst with which the hydrocarbon vapors are brought into contact may be maintained extremely uniform. Further, an exceptionally uniform and complete regeneration of the catalyst is attained and the catalyst is efiectively freed from catalyst fines in the final regenerating step. The use of the present apparatus in carrying out such conversion operations has the advantage of high uniformity of the product, increased catalyst life and catalytic efiectiveness, increased economy of operation, by reason of the elimination of mechanical conveyors, and also an exceptionally close control of operating conditions.

I claim:

1. Apparatus especially adapted to the conversion of hydrocarbons which comprises an 1 enlarged elevated chamber, a coaxially positioned, vertically elongated, annular chamber extending downwardly therefrom, a plurality of outer, vertically spaced annular chambers, encircling the elongated vertical chamber, a plurality of inner, vertically spaced annular chambers encircled by the inner wall of the vertically elongated chamber, the relative positions of the inner and outer vertically spaced chambers being staggered so that the upper portion of an inner chamber is opposite the lower portion of an outer chamber and the lower portion of said inner chamber is opposite the upper portion of the next lower outer chamber, each inner and outer chamber communicating with the vertically elongated annular chamber through louvers in the walls of the latter, the slats of the louvers extending upwardly into the respective vertically spaced chambers, a hopper beneath the lower end of the vertically elongated chamber and communicating therewith through an annular connection, a separate chamber adapted to contain a body of finely divided solid at an elevated temperature, a conduit leading to the separate chamber, a connection for injecting a gas communicating with the last said conduit, a conduit connecting the lower end of the hopper with the last said conduit at a point downstream from Where the last said connection communicates therewith, a conduit leading upwardly to the lower end of the enlarged elevated chamber, a connection for injecting reactant vapors communicating with the lower end of the last said conduit, a conduit con-' necting the separate chamber with the lower end of the last said conduit at a point downstream from where the last said connection communicates therewith, conduit connections to the lower and at least two intermediate, vertically spaced outer annular chambers, respectively, and a connection between the upper end of the enlarged elevated chamber and the uppermost of the outer, vertically spaced chambers.

2. Apparatus especially adapted to the conversion of hydrocarbons which comprises an enlarged elevated chamber, a coaxially positioned, vertically elongated, annular chamber extending downwardly therefrom, a plurality of outer,

vertically space annular chambers encircling the elongated vertical chamber, a plurality of inner, vertically spaced annular chambers encircled by the inner wall of the vertically elongated chamber, the relative positions of the inner and outer vertically spaced chambers being staggered so that the upper portion of an inner chamber is opposite the lower portion of an outer chamber and the lower portion of said inner chamber is opposite the upper portion of the next lower outer chamber, each inner and outer chamber communicating with the vertically elongated annular chamber through louvers in the walls of the latter, the slats of the louvers extending upwardly into the respectively vertically spaced chambers, a hopper beneath the lower end of the vertically elongated chamber and communicating therewith through an annular connection, flow control mechanism adapted to control the flow of finely divided solid through the annular connection, a separate chamber adapted to contain a body of finely divided solid at an elevated temperature, a conduit leading to the separate chamber, a connection for injecting a gas communicating with the last said conduit, a conduit connecing the lower end of the hopper with the last said conduit at a point downstream from where the last said connection communicates therewith, a conduit leading upwardly to the lower end of the enlarged elevated chamber, a connection for injecting reactant vapors communicating with the lower end of the last said conduit, a conduit connecting the separate chamber with the lower end of the last said conduit at a point downstream from where the last said connection communicates therewith, conduit connections to the lower end at least two intermediate, vertically spaced outer annular chambers, respectively, and a connection between the upper end of the enlarged elevated chamber and the uppermost of the outer vertically spaced chambers.

3. The apparatus of claim 2 further characterized in that the flow control mechanism comprises a ring positioned in a horizontal plane coaxial with and beneath the annular connection, the ring being at least coextensive with the lower end of the annular connection and adapted to be moved toward and away from the lower end of said annular connection.

KENNETH MERLE WATSON.

No references cited. 

1. APPARATUS ESPECIALLY ADAPTED TO THE CONVERSION OF HYDROCARBONS WHICH COMPRISES AN ENLARGED ELEVATED CHAMBER, A COAXIALLY POSITIONED, VERTICALLY ELONGATED, ANNULAR CHAMBER EXTENDING DOWNWARDLY THEREFROM, A PLURALITY OF OUTER, VERTICALLY SPACED ANNULAR CHAMBERS, ENCIRCLING THE ELONGATED VERTICAL CHAMBER, A PLURALITY OF INNER, VERTICALLY SPACED ANNULAR CHAMBERS ENCIRCLED BY THE INNER WALL OF THE VERTICALLY ELONGATED CHAMBER, THE RELATIVE POSITIONS OF THE INNER AND OUTER VERTICALLY SPACED CHAMBERS BEING STAGGERED SO THAT THE UPPER PORTION OF AN INNER CHAMBER IS OPPOSITE THE LOWER PORTION OF AN OUTER CHAMBER AND THE LOWER PORTION OF SAID INNER CHAMBER IS OPPOSITE THE UPPER PORTION OF THE NEXT LOWER OUTER CHAMBER, EACH INNER AND OUTER CHAMBER COMMUNICATING WITH THE VERTICALLY ELONGATED ANNULAR CHAMBER THROUGH LOUVERS IN THE WALLS OF THE LATTER, THE SLATS OF THE LOUVERS EXTENDING UPWARDLY INTO THE RESPECTIVE VERTICALLY SPACED CHAMBERS, A HOPPER BENEATH THE LOWER END OF THE VERTICALLY ELONGATED CHAMBER AND COMMUNICATING THEREWITH THROUGH AN ANNULAR CONNECTION, A SEPARATE CHAMBER ADAPTED TO CONTAIN A BODY OF FINELY DIVIDED SOLID AT AN ELEVATED TEMPERATURE, A CONDUIT LEADING TO THE SEPARATE CHAMBER, A CONNECTION FOR INJECTING A GAS COMMUNICATING WITH THE LAST SAID CONDUIT, A CONDUIT CONNECTING THE LOWER END OF THE HOPPER WITH THE LAST SAID CONDUIT AT A POINT DOWNSTREAM FROM WHERE THE LAST SAID CONNECTION COMMUNICATES THEREWITH, A CONDUIT LEADING UPWARDLY TO THE LOWER END OF THE ENLARGED ELEVATED CHAMBER, A CONNECTION FOR INJECTING REACTANT VAPORS COMMUNICATING WITH THE LOWER END OF THE LAST SAID CONDUIT, A CONDUIT CONNECTING THE SEPARATE CHAMBER WITH THE LOWER END OF THE LAST SAID CONDUIT AT A POINT DOWNSTREAM FROM WHERE THE LAST SAID CONNECTION COMMUNICATES THEREWITH, CONDUIT CONNECTIONS TO THE LOWER AND AT LEAST TWO INTERMEDIATE, VERTICALLY SPACED OUTER ANNULAR CHAMBERS, RESPECTIVELY, AND A CONNECTION BETWEEN THE UPPER END OF THE ENLARGED ELEVATED CHAMBER AND THE UPPERMOST OF THE OUTER, VERTICALLY SPACED CHAMBERS. 